The present invention is related to passenger detection systems, and in particular to passenger detection systems that can readily classify an attribute of a passenger of an automobile in which an air bag device is installed.
Air bag devices ease the shock that a passenger experiences during an automobile collision. Air bags are installed in front of the driver""s and passenger""s seats. Air bags may be installed in other locations, such as to the side of a forward facing passenger.
Many air bags are designed to deploy in front of the torso of an adult passenger seated in the seat. When a rear facing infant seat (hereafter RFIS) is located on the front passenger seat, it is desirable for the passenger-side air bag not to deploy. It may also be desirable for the passenger-side air bag not to deploy for a forward facing child seat (hereafter xe2x80x9cFFCSxe2x80x9d), child or small adult. Likewise, deployment may be limited for side impact airbags based on whether a child or short person is leaning towards the air bag. Other reasons for preventing or limiting deployment (e.g. deploying with less force) may exist.
Passenger detection sensor types have been proposed for detecting a RFCS, an FFCS or children. Systems using electric fields to detect characteristics of a load in a seat are disclosed in U.S. Pat. No. 5,948,031, 6,329,913 (Ser. No. 09/413,099, filed Oct. 5, 1999), U.S. Pat. No. 6,329,914 (Ser. No. 09/678,215, filed Sep. 29, 2000) and pending application Ser. No. 09/798,788, filed Mar. 2, 2001). Other systems using capacitive sensing, such as systems to detect a change in phase or frequency due to the presence of a passenger, have also been proposed. Both types of systems rely on transmission and reception from one or more antenna or electrodes.
Other passenger detection systems use ultrasound, infrared, electromagnetic energy or other transmissions or receptions to detect one or more characteristics of occupants. Yet another type of detection system uses weight sensors, strain gauges, pattern recognition or other techniques or devices.
Occupant detection sensors are often positioned on the floor, in the seat or in other areas subjected to liquid. Liquid, such as from spilled drinks, baby leaks, pet accidents, open windows, open sunroofs or other sources, may alter the performance of the sensor. Any of the sensors discussed above or other sensors now known or later developed may operate differently due to liquid on or near the sensor.
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiments described below include systems and methods for compensating for liquid, such as spills. Measured values of an occupant detection system are adjusted as a function of the relationship of the one or more measured parameters to an amount of liquid. One such relationship is a square or cube root function. The affects of liquid are also compensated by: covering occupant detection sensors with a moisture resistant covering and/or forming a drain in a seat cushion to remove liquid from near sensors adjacent the seat cushion.
Further aspects and advantages are described below.